Designing a Computer System to Hack, Help for a newer GM Options

[Dewar]

I'm not a total newbie when it comes to Shadowrun 4th ed, but this is the first game I've run where hacking is being emphasised, and I want to get it right. Here's how I've designed my network.

The building has two machines directly connected to the Matrix, one which is a fairly average system that all the normal traffic goes through, and the other that's a VPN to the regional office, so it's subscribed only to the regional office's computer. Both of those connect to a central system where all of the various user machines and file servers and what not connect together. Finally, there's a security computer connected to that which is in turn connected to all the cameras and door locks.

So for each of these nodes, what stats do I need to list? Obviously they'll each need a Response, Firewall, and System stat. What other things do I need? I want this to be a pretty easy target since this is their first run, but I also want that VPN server to be tempting, and to swat down anyone who's feeling overconfident.